I am learning about the basics of electronics.

I bought an LS7220 chip for a keypad lock, but using it turned out more difficult than I expected. I have attached it to a 9v battery at pins 9 and 14, sent voltage once to pin 1 (sense in), and then checked the voltage between pin 8 (lock status out) to ground. My multi-meter is not giving me the results that I would expect.

Since I have run into trouble at such an early stage, I fear this is because I am sending 9V to the pin, and I am not using any resistors.

How do I send HIGH and LOW, I assume there is a specific voltage so I should use a resistor or something? Unless absolutely necessary, I do not want to connect this to an Arudino. What else am I doing wrong at such an early stage, where I just want to check the output of pin 8 (lock status out)?

If someone could show me how to wire this up, just to sense input and let me check the locked status of the lock it would be helpful.

When the SENSE INPUT goes high, The LS7220 is enabled. The Lock Status output turns on and Save Status and LOCK outputs remain off. When the programmed four-digit combination is entered from the keypad, in proper sequence, lock turns on and Lock Status turns off.

  • \$\begingroup\$ I imagine you have to input the correct code before it releases the lock, no? \$\endgroup\$
    – Hearth
    Jun 24, 2021 at 14:55
  • \$\begingroup\$ @Hearth By default, the PIN 8 should be HIGH for locked, until the correct passcode is entered. \$\endgroup\$
    – questioner
    Jun 24, 2021 at 15:04
  • 1
    \$\begingroup\$ Not without a pullup resistor, it appears. Looks like it's an open-drain output. \$\endgroup\$
    – Hearth
    Jun 24, 2021 at 15:06
  • \$\begingroup\$ Well, if someone posts an answer with a picture of what should go where I would appreciate it. I am not asking for the full project, just the small request in my question so I have a leg to stand on. \$\endgroup\$
    – questioner
    Jun 24, 2021 at 15:15


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